Guest ZmeFly Posted December 12, 2000 Share Posted December 12, 2000 I'm just getting into the V8 scene must say I really like especially since i took the car for a ride yesterday and you should have seen all the face when that little 280 of mine rolled by going bababbabab you know the nice deep rumble of that V-8 coming out of the pipes. but anyway, it seems like the carb is getting tooooo much fuel. goes threw gas like its throwing it on the road. and when I'm driving I can now and then smell gas also. does anyone have any ideas??? I would sure appreciate it thanks guys ------------------ Quote Link to comment Share on other sites More sharing options...
Guest Frank280z Posted December 12, 2000 Share Posted December 12, 2000 I guess you could start by turning the mixture screws in all the way and backing out 1 1/2 to 2 turns to start. Check for vaccuum leaks.....Where is Uniontown? I'm up in the NE section of PA. Frank ------------------ Build it. Drive it. Improve it. Quote Link to comment Share on other sites More sharing options...
Modern Motorsports Ltd Posted December 12, 2000 Share Posted December 12, 2000 Great to hear it's going:-) HP Books 'Rochester Carbeurators by Doug Roe' is a good qjet book As Frank says the mixture screws affect idle/light throttle in varying ways. What worked really well for me on tuning my qjet for light throttle was this... -start with screws where they are or go all thy way in and then out as Frank says (don't turn in too tight! you can damage them), then progressively turn in both screws a 1/4 turn -take it out and in 1st gear run it up to 3k/4k rpm or so and back right off....when you back off if you get an intake 'popcorn' you're lean, if not lean progressively go in until you are, once you are back one out at a time 1/8 turn until the popcorn (you'll hear some harmless popping at the air filter area) is gone and I found that my best set. This assumes your timing etc is close in the ballpark as retarded timing can have similar symptoms so's you know. (found this worked great before I started getting more of the tools I have now) Do you plugs look v. rich? If they do then your idle/part throttle is rich as you say. (unless you shut off right after full throttle it's pretty much idle/light throttle you'll read on them, other than left over damage from WOT). Are your secondaries coming in fine? (ie. no bog) if so great....If you get into the secondaries/rods/hangars I have collection of parts if you need a different combo. ------------------ Of all the things I've lost, I miss my mind the most. Quote Link to comment Share on other sites More sharing options...
John Scott Posted December 12, 2000 Share Posted December 12, 2000 Sometimes on older Qjets have leaky fuel wells. A dab of epoxy underneath sometimes gives them more life. I agree to check your plugs and jet to cruise surging, then back richer a number or two. Secondary bogs are usually the airvalve tension spring. Mini hex lock on passenger side of rear butterfly air valve. Loosen and with screw driver in spring adjustment tighten slightly 1/4 increments for bog. When you get a clean transition to idle to power, driving conditions, not winging it in neutral that is, then play with the hangers/ rods. Usually don't need to get into the primary side. If you can get the book(s) on Qjets. They really do make nice street carbs. JS Quote Link to comment Share on other sites More sharing options...
pparaska Posted December 12, 2000 Share Posted December 12, 2000 A local buddy with a 350 in his 240Z has been having trouble with his 600 vac sec Holley. It's been gone through and then runs crappy after a while. Since he's not interested in messing with it any longer, he decided to getr a new carb. He was considering the new versions of the Edelbrock Performer carb (carter-like). He went to the engine builder/speedshop that built his engine and asked the owner's advice. This guy has been doing street and race American stuff for over 20 years - Guy(?) Mancini. Mancini said that all the street motors he sends out as complete units have an Edelbrock Quadrajet on them! My buddy and I were very surprised to here that. Mancini said that the he's seen alot of motors have their cylinders washed down when they used the Edelbrock Performer carbs. He likes the simplicity of the Holley, but prefers the Edelbrock Quadrajet for street use. Just some food for thought. I've always known that the Quadrajet was a great street carb if it was tuned well. My problem is that my attempts years ago (when I knew less and was much less thorough) at rebuilding them were far from successful. I guess I might go that way if my 750 vac sec (on the motor) and the 600 vac sec I have stashed away don't make me happy. Damn, I wish EFI weren't so expensive! ------------------ Pete Paraska - 73 540Z - Marathon Z Project pparaska@home.com Pete's V8 Datsun 240Z Pages Quote Link to comment Share on other sites More sharing options...
Guest ZmeFly Posted December 12, 2000 Share Posted December 12, 2000 thanks for all the info fellas i really appreciate it. now only one more thing and it will be ready for sure. thanks again james aka ZmeFly Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted December 13, 2000 Share Posted December 13, 2000 I bought a q-jet carb off of ebay for $35. The guy said it came off of a corvette, but I forgot to ask what year, and I forgot to ask what CFM the carb is. Does anyone have any idea or a good guess what CFM my carb is? ~Brian Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted December 13, 2000 Share Posted December 13, 2000 quote: Originally posted by Head: I bought a q-jet carb off of ebay for $35. The guy said it came off of a corvette, but I forgot to ask what year, and I forgot to ask what CFM the carb is. Does anyone have any idea or a good guess what CFM my carb is? ~Brian Depends on the year and engine, but probably in the 6-700 cfm range. Hopefully its really off a chevy corvette, cause they're hard to tell apart and GM made bunches of models of them. Lone [This message has been edited by lonehdrider (edited December 12, 2000).] Quote Link to comment Share on other sites More sharing options...
Guest Tom Scala Posted December 15, 2000 Share Posted December 15, 2000 Rich running with a Q-Jet could be leakage in the casting itself dumping fuel into the intake manifold. This is a notorious problem with older units. Look at the well plugs in the bottom of the float bowl. You can sometimes seal them with epoxy but this is temporary. Is it hard to start after sitting for a few days? This is a sign of leaky well plugs since the float bowl will be near empty from the leakage and you'll have to crank the motor to fill it up again. Quote Link to comment Share on other sites More sharing options...
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